Harry Chapman Pincher, the journalist and author dubbed "the great spy-catcher of Fleet Street" in an extraordinary career at the Daily Express, has died aged 100.

Pincher, who celebrated his 100th birthday in March, unearthed reams of military secrets during a 30-year career as the defence and science correspondent of the Daily Express, then Britain's biggest-selling newspaper.

He retired from the paper in 1979, going on to publish a series of controversial books on espionage. His most explosive, Their Trade is Treachery, revealed that the former MI5 head Sir Roger Hollis had been investigated as a suspected Soviet spy.

Pincher's son, Michael Chapman Pincher, announced his father's death on his Facebook page on Tuesday night. He said: "Our dad, Chapman Pincher (The Lone Wolf of Fleet Street) facing his death with: no regrets, no fear and no expectation, died of old age on 05 August 2014 aged hundred and a quarter. 'Harry' a journalist, author, fisherman, shot and scourge of politicians of all hues leaves Pat and Mick, a raft of grandchildren, his third wife Billiee and her three children. His last joke was 'Tell them I'm out of scoops.' For him RIP stands for Recycling-in-Progress."

He told the Guardian that Chapman Pincher died of old age, having suffered a mini-stroke about seven weeks ago. "While he was still coherent I was reminding him about his glory days and he just said, 'Now I'm all out of scoops'. That was his last joke."

A keen writer to the last, Chapman Pincher published his last book in February this year – a memoir titled Dangerous to Know. He was said to have been working on another. Renowned for his high-level contacts in government, scientific and military establishments, Chapman Pincher enjoyed a string of exclusives in the 1950s and 60s. In interviews to mark his 100th birthday on 28 March, he said he "pioneered a kind of investigative journalism" by meeting all the top people over lunch "because that's where the stories lay".

His Daily Express exposés caused untold misery for successive governments. Harold Macmillan wrote to his defence secretary at one point: "Can nothing be done to suppress or get rid of Mr Chapman Pincher?"

Born in Ambala, India, in 1914, his real name was Harry but he took on the moniker Chapman Pincher to satisfy his Daily Express editors, who preferred a more posh name.

Michael Chapman Pincher said he would hold a small family gathering in the next week to celebrate his father's life. He added that he had discovered a "whole series of letters and memos from prime ministers, admirals, generals, all sorts of people" while tidying his father's Queen Anne home in west Berkshire recently, which he planned to put in a box as keepsakes.

He said: "As a journalist, I asked him what his most difficult story was, and his most difficult story was announcing that there was a connection between smoking and lung cancer. He went into an editorial meeting, which in those days was a fog of smoke and booze, and everyone turned on him as if it was the worst story in the world. The thing he was most proud of was that he never had to retract a story.

"As a family man, he was the only child of an only child of an only child, so he grew up in a very small nuclear family. He never had to compromise with anyone as you do in a normal family and so for me it was only really in the last year of his life that we became pals. That was a great pleasure because an important man is a difficult shadow to live under. He wasn't a great family man, but did become a great pal in the end."

The Channel 4 News presenter Jon Snow paid tribute to the "good, old-fashioned hack" in March. He wrote: "He remains remarkably spry, sitting bolt upright in a comfy army chair in his living room, with his 95-year-old wife, Billee, sitting a few feet behind him, supping her midday sherry. I've been to meet them both in their Queen Anne home in west Berkshire.

"Harry seems to have set his mind some years ago on getting to 100. He hasn't drunk alcohol since he retired 35 years ago, hasn't smoked cigarettes ever, and abandoned his pipe upon joining the army in the second world war.

"His fear is of falling over – so he no longer goes out. But he is on his computer, keeping abreast of the world every day. He is by degrees lucid, funny, naughty and and unashamed to boast both of his luck and of his scoops."